This tutorial, Part 2 , outlines how to create a custom Ultiboard landpattern for layout. This landpattern is created manually so as to precisely define the shape, size, and dimensions of a Surface Mount Device (SMD).The article will outline the steps to create a custom 20-pin SMD landpattern that can be associated with the custom component created in the Creating a Custom Component in NI Multisim tutorial.
Steps in the creation process include:
Please note: The landpattern you are creating in this tutorial is not a commercial package. The pad and package dimensions and spacing are used primarily to showcase an effective design procedure in Ultiboard.
The term landpattern and footprint will be used interchangeably throughout this tutorial.
Ultiboard and Multisim both share a common database structure which organizes the various components into logical groups. The creation task therefore begins in the Ultiboard Database Manager.
Figure 1 - Database Manager
Figure 2 - Select Part
The Ultiboard design area will now be in the ‘Footprint edit mode’ and display the x?? symbol (Figure 3). x? represents the Reference Designator (RefDes) and ? represents the Value of the component. These values will be edited later in the design process in Step 4.
Figure 3 - Footprint Edit Mode
It is important to begin the design process by setting the units of measurements for the landpattern design grid. When placing components, the design grid is what objects will snap to when they are being moved and/or placed. The grid spacing therefore defines the degree of precision with which objects can be placed in the work-area.
Figure 4 - Grid Properties
With these settings both components and copper will be placed on a 1 mil by 1 mil design grid.
Both THT (through-hole technology) pins and SMD (surface mount device) pads can be placed onto a custom landpattern. The following steps will outline how to add an array of SMD pads.
Figure 5 - Pin Properties Dialog
You will now define a 10 by 2 array of SMD pins for our custom landpattern.
Table 1: Pin Dimensions
The top field described the shape of the pad. Other options include Round, Rectangle etc…
The pin length defines the vertical dimension of the pin
The pin width defines the horizontal dimension of the pin
In the case of rounded objects, the pin radius defines the radius of the circular part of the object
Figure 6 - Set SMD Pin Properties
Table 2: Pin Spacing
The center-to-center vertical spacing between adjacent pins.
The center-to-center horizontal spacing between adjacent pins.
The number of rows in the pin array
The number of columns in the pin array
Note: The above dialog settings can be changed to fit your specific landpattern. For example, if both Rows and Columns are set to 1, you can place individual pins.
Figure 7 - Set SMD Pin Spacing
Pin 1 of the pin array is the upper-left pad and is attached to the mouse cursor. To accurately place the pad so that the reference point is in the middle of the pad press the asterisk key (*) on the right number pad (not shift + 8). Laptop users must press FN + 0.
The Ultiboard work area will now appear as in Figure 8. You will notice that our pins are oriented incorrectly (vertically, rather than horizontally) and must be rotated by 90 degrees.
Figure 8 - Pin Setup
Figure 9 - Select Toolbox (SMD Pads)
Figure 10 - Pin Angle
Figure 11 - Final SMD Pin Orientation
During the creation of a new landpattern pins may be placed onto the design in a random order. It may therefore become necessary to edit the value associated with each pin so that they are numbered sequentially around a package.
Figure 12 - SMD Pin Properties
Figure 13 - SMD Pin Attributes
In general a package such as this has the pins numbered sequentially in a counter-clockwise direction. Therefore pin 10 should be in the bottom left-hand corner and pin 11 in the bottom right-hand corner. The final pin number configuration for this design should be as in Figure 14. Therefore to change the pin number;
Figure 14 - Component Pin Setup Map
In Figure 11 you will continue to notice the x?? symbol, which represents the Reference Designator and Value of the landpattern.
The Reference Designator is the key identifier of the component and is represented as x?. This x can be changed so that it corresponds with the type of component it is associated with. For example, if this landpattern was for a resistor this value could be set to R. The ? represents a number to denote the different components in a design. So, returning to the example of a resistor, the resistors placed onto a design, would be named R1, R2, R3 etc…
Value, represented by the ? symbol, is the physical value of the component. Taking the example of the resistor into consideration once more, the ? could equal 20k for 20 Kohms.
In this step you will select, move and alter the RefDes and value.
Figure 15 - Select Toolbox (Selecting Attributes)
The RefDes and Value are currently overlapping the landpattern placement as shown in Figure 11.
Figure 16 - REFDES Attribute Properties
When the custom component is now placed the RefDes for the landpattern will be U1, U2, U3 etc…
Generally the Value attribute, ?, is set to either visible or invisible depending on the need to highlight the value of the landpattern on the final design. In this example, it will be set to invisible.
Both along the top and left side of the Ultiboard design area are the ruler bars in Figure 11. If the ruler bars cannot be seen, go to View >> Ruler Bars. These ruler bars allow the positioning of dashed lines to align shapes from one object to the next, precisely within the design area. For the following steps refer to Figure 14 for the pin numbers.
Figure 17 - The Ruler Bar
These markers will now act as a guide on where to begin the placement of the landpattern shape on the silkscreen layer in step 7.
If at any time markers need to be cleared, you can right-click on a specific marker and select Clear, or select Clear All to remove all markers.
The placement of shapes on the silkscreen layer defines how the custom component will appear in your design. It represents the physical dimensions of the package. In this step you will utilize the ruler markers set up in step 4 to place a rectangular landpattern shape.
Figure 18 - Design Toolbox
Figure 19 - Select Toolbox (Select Other Objects)
Figure 20 - Rectangle Properties
The landpattern will now appear as shown in Figure 21.
Figure 21 - Final Landpattern
In Ultiboard a design can be previewed in 3D to virtually represent the final design. In order to setup the custom landpattern for this 3D preview, the necessary information should be setup at the creation stage.
Figure 22 - 3D Rectangle Properties
Table 3: 3D Information
Enable 3D for this object
Enables Ultiboard to render a 3D object
The height in mils of the 3D object
The offset height from board
Use 2D data to create 3D shape
Uses the 2D shape on the silkscreen layer to create the package shape
Creates a solid 3D representation
Figure 23 - 3D Settings
Table 4: 3D Pins
Angle to Pad
Sets the angle at which Ultiboard will render the pin connections with respect to the package.
Defines the shape of the 3D pin
Renders the specific type of pin
In the 3D Preview you should immediately notice that the pins on the left side of the component face away from the package. This is because by default, the leads on a horizontal SMD pin will be directed towards the left. Therefore the pins must be re-orientated towards the package by rotating them 180 degrees.
Recall, in step 3 that the pins were set to 90 degrees for a horizontal orientation.
Due to this 90 degree rotation, we must rotate an additional 180 degrees, in the above step so that the 3D leads are now directed towards the component. 90 + 180 = 270 degrees.
If you double click in the black work-area and select the tab for 3D data you will notice that as in Figure 24, the pins are properly positioned with respect to the 3D package.
Figure 24 - 3D Pin Settings
With the landpattern created all that remains is saving the to the Ultiboard database.
Figure 25 - Save Dialog Box
Before a custom landpattern can be utilized in Multisim, it must be added to the database. Once added to the database, it can be seen as an available landpattern, or footprint, and added to a component.
In this step, the SMD20 tutorial landpattern created will be associated with the symbol created in Part 1 of the tutorial.
Figure 26 - Multisim Database Manager
Table 5: Add a Footprint
The database in which you saved the landpattern in Ultiboard
An additional manufacturer identifier
This is a CASE SENSITIVE field, and must identify the landpattern exactly as it is saved in Ultiboard
This is a CASE SENSITIVE field. While the Footprint field identifies the specific package name of the component it can be associated with the Ultiboard Footprint so that a generic footprint with the same dimensions can be transferred to layout
Number of Pins
Number of pins on the landpattern
The type of pin technology Surface Mount or Through Hole
Figure 27 - Add a Footprint
Success!! You have created a custom Ultiboard landpattern, defined a 3D model and associated it to a Multisim symbol.
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